| Acknowledgments |
4 |
| List of Acronyms |
5 |
| Abstract |
10 |
| 1. Introduction |
11 |
| 1.1 Why Attention to Outdoor Lighting is Important |
11 |
| 1.2 How to Use This Technical Note |
13 |
| 2. Night Sky and Darkness Values |
15 |
| 2.1 Aesthetic, Spiritual, and Wilderness Values of Night Skies |
16 |
| 2.2 Historic and Cultural Values of Night Skies |
16 |
| 2.3 Recreation Values of Night Skies |
18 |
| 2.4 Astronomical and Scientific Values of Night Skies |
19 |
| 2.5 Biological Values of Natural Darkness and Night Skies |
19 |
| 2.6 Night Sky and Darkness Values in Relation to BLM-Managed Lands |
20 |
| 3. Light Pollution: Exposure Mechanisms
and Effects |
22 |
| 3.1 Basics of Light and Light Pollution |
23 |
| 3.1.1 Light Qualities |
23 |
| 3.1.2 Types of Light Pollution |
24 |
| 3.1.3 How Distance Affects Light Pollution |
27 |
| 3.2 Exposure Mechanisms: How Artificial Light at Night Affects Humans |
28 |
| 3.2.1 Increase in Brightness of the Night Sky |
28 |
| 3.2.2 Effects on Visibility of Objects in Dark or Near-Dark Conditions |
29 |
| 3.2.3 Too Little or Too Much Light |
30 |
| 3.2.4 Light Trespassing Where It Is Not Wanted |
30 |
| 3.3 Effects of Artificial Light at Night on Humans |
30 |
| 3.3.1 Aesthetic, Spiritual, and Recreational Effects |
30 |
| 3.3.2 Historic and Cultural Effects |
31 |
| 3.3.3 Astronomical and Scientific Effects |
32 |
| 3.3.4 Nuisance Effects |
32 |
| 3.3.5 Human Health Effects |
33 |
| 3.3.6 Economic Effects |
33 |
| 3.4 Exposure Mechanisms: How Artificial Light at Night Affects Animals and Plants |
34 |
| 3.4.1 Temporal Niche Partitioning in Animals |
35 |
| 3.4.2 Role of Darkness in Biological Repair and Recovery |
36 |
| 3.4.3 Photoperiodism and Circadian Rhythms in Animals and Plants |
36 |
| 3.4.4 Visual Perception in Animals |
36 |
| 3.4.5 Spatial Orientation and Navigation in Animals |
37 |
| 3.4.6 Photosynthesis in Plants |
37 |
| 3.5 Effects of Artificial Light at Night on Animals and Plants |
37 |
| 3.5.1 Effects of Artificial Light at Night on Animals |
37 |
| 3.5.1.1 Effects on Insects and Other Arthropods |
38 |
| 3.5.1.2 Effects on Mammals |
39 |
| 3.5.1.3 Effects on Birds |
40 |
| 3.5.1.4 Effects on Reptiles |
41 |
| 3.5.1.5 Effects on Fish |
42 |
| 3.5.1.6 Effects on Amphibians |
42 |
| 3.5.2 Effects of Artificial Light at Night on Plants |
43 |
| 4. Principles of Artificial Light at Night to Avoid Light Pollution |
44 |
| 4.1 Light Only If Needed: Use Alternatives to Permanent Lighting |
45 |
| 4.2 Light Only When Needed: Use Lighting Control Technologies |
45 |
| 4.3 Light Only Where Needed: Shield Lights and Direct Them Properly |
46 |
| 4.4 Light Color Matters: Select Amber, Orange, or Red Whenever Possible |
46 |
| 4.5 Use the Minimum Level of Illumination Necessary: Avoid Over-Illumination |
47 |
| 4.6 Use Energy-Efficient Lights and Advanced Lighting Controls: Save Energy While Adding Useful Lighting Capabilities |
47 |
| 5. BMPs for Artificial Light at Night on
BLM-Managed Lands |
48 |
| 5.1 Planning and Design BMPs |
50 |
| 5.1.1 Have a Lighting Plan Prepared by a Qualified Lighting Designer |
50 |
| 5.1.2 Select Outdoor Luminaires Certified to Minimize Light Pollution |
51 |
| 5.1.3 Consider Using an Energy Savings Performance Contract (ESPC) for Lighting |
55 |
| 5.1.4 Take Advantage of DOE Assistance for Outdoor Lighting |
55 |
| 5.1.5 Consider Nearby Astronomical Observatories before Installing Lighting Systems |
56 |
| 5.1.6 Educate Stakeholders Concerning Night Sky and Darkness Resources |
56 |
| 5.1.7 Keep Informed about Lighting Best Practices |
57 |
| 5.1.8 Identify Light-Sensitive Receptors |
57 |
| 5.1.9 Conduct a Baseline Study of Existing Light Pollution and Night Sky Conditions |
57 |
| 5.1.10 Conduct an Inventory of Existing Lighting When Retrofitting |
59 |
| 5.1.11 Establish a Lighting and Light Pollution Monitoring Program |
60 |
| 5.2 BMPs for Lighting Only If Needed |
60 |
| 5.2.1 Critique New or Evaluate Existing Lighting Systems |
60 |
| 5.2.1.1 Consider Essential Light Sources Associated with a Built Environment |
61 |
| 5.2.1.2 Consider Nonessential Light Sources Associated with a Built Environment |
61 |
| 5.2.2 Consider Dark Adaptation Needs of People and Wildlife |
61 |
| 5.2.3 Encourage Alternatives to Permanent Lighting for Infrequent Lighting Needs |
62 |
| 5.3 BMPs for Lighting Only When Needed |
63 |
| 5.3.1 Use Lighting Controls to Limit Lighting to Specified Periods |
63 |
| 5.3.2 Switch Off or Dim Lighting during Times of Critical Biological Activity |
64 |
| 5.3.3 Include Lighting Season/Date Restrictions in Operations Permits |
64 |
| 5.3.4 Use Aircraft Detection Lighting System (ADLS) Technology for Hazard Navigation Lighting |
65 |
| 5.4 BMPs for Lighting Only Where Needed |
65 |
| 5.4.1 Direct Light Only Where It Is Needed |
65 |
| 5.4.2 Do Not Aim Lights Upward, Horizontally, or at Large Angles from the Ground |
66 |
| 5.4.3 Re-Aim Existing Lights to Illuminate Task Targets |
66 |
| 5.4.4 Use Dark Sky-Compliant Luminaires |
66 |
| 5.4.5 Use Luminaires with an IES TM-15-20 BUG Rating System Uplight (U0) Rating |
67 |
| 5.4.6 Retrofit Existing Poorly Shielded Lights with Luminaires with a BUG U0 Rating |
67 |
| 5.4.7 Where Necessary, Install Customized Shielding |
67 |
| 5.4.8 Use Low-Height, Fully Shielded Step or Path Lights |
68 |
| 5.4.9 Install Window Coverings Inside Buildings |
68 |
| 5.4.10 Mount Lights at the Proper Height |
68 |
| 5.4.11 Install Lights at the Tops of Signs and Buildings, Pointing Downward |
68 |
| 5.4.12 Avoid the Use of Swivel-Mounted Floodlights |
69 |
| 5.4.13 Avoid Uplighting Where Possible |
69 |
| 5.4.14 Screen Lighting Where Possible |
70 |
| 5.4.15 Use Pole-Mounted Lights with Low BUG Ratings for Backlight Close to Property Boundaries |
70 |
| 5.4.16 Use Forward Throw Asymmetric Luminaires Where Appropriate |
70 |
| 5.4.17 Choose Roadway Luminaires to Maximize Lighting the Road and Minimize Lighting Away from the Road |
71 |
| 5.4.18 Use Lighting Transition Zones between Brightly Lit and Unlit Areas |
71 |
| 5.4.19 Leave Gaps in Long Linear Arrangements of Lights |
71 |
| 5.4.20 Provide Dark Corridors to Facilitate Animal Movement |
71 |
| 5.5 BMPs for Light Color Matters: Select Amber, Orange, or Red When Possible |
71 |
| 5.5.1 Use “Night Sky Friendly” Narrow-Spectrum Amber, Orange, or Red Light Sources |
72 |
| 5.5.2 Use Tunable CCT Lighting to Adjust Color of Light Sources |
72 |
| 5.5.3 Consider Melanopic/Photopic Ratio When Selecting Light Sources |
73 |
| 5.5.4 If Necessary, Remove UV Light Content with Filters or Housings |
73 |
| 5.5.5 Use Consistently Colored Light Sources |
73 |
| 5.6 BMPs for Minimizing the Level of Illumination |
73 |
| 5.6.1 Use the Lowest Possible Level of Illumination that Meets the Lighting Needs |
73 |
| 5.6.2 Reduce Light Levels of Security Cameras to the Minimum Required for Proper Functioning |
74 |
| 5.6.3 Replace Existing Lights with
Lower-Output Light Sources |
74 |
| 5.6.4 Use Dimming Lighting Controls to Reduce Over-Illumination |
74 |
| 5.6.5 Dim Lighting by 30 to 50 Percent after High Traffic Hours in Public Spaces that Must Stay Illuminated |
75 |
| 5.6.6 For Tall Structures, Use Flashing Warning Lights at Night, and Replace Nonflashing with Flashing Lights |
75 |
| 5.6.7 Where ADLS Technology Is Not Used, Use the Minimum Amount of Hazard Navigation Lighting Specified by the FAA |
76 |
| 5.6.8 Use Reduced Intensity Lights with Short Flash Durations for Hazard Navigation Lighting |
76 |
| 5.6.9 Use Enclosed Flare Systems for Gas Flaring Associated with Oil and Gas and Similar Operations |
77 |
| 5.6.10 Where Decreased Visibility Is Desired, Reduce Reflectivity of Illuminated Surfaces |
77 |
| 5.7 BMPs for Energy-Efficient Lights and Advanced Lighting Technology |
78 |
| 5.7.1 Use Energy-Efficient Lights with Advanced Lighting Technology |
78 |
| 5.7.2 Consider the Total Life Cycle Cost When Selecting New Lighting Systems or Retrofitting Existing Systems |
78 |
| 5.7.3 Inspect and Clean Luminaires Regularly |
78 |
| 6. Summary |
79 |
| 7. Glossary |
80 |
| 8. References |
86 |